SU665382A1 - Ac-to-dc converter - Google Patents

Description

one

This invention relates to converters of AC energy to rectified energy with deep regulation of the output voltage. Such transducers are used, for example, in an electric drive and as an adjustable power source.

Converters are known in which deep regulation of the rectified voltage is provided by phase control of the thyristor arms of the rectifier 1. In rectifier circuits without artificial quenching, the thyristors are turned on with an adjustable phase angle a and are switched off under the action of the supply voltage, which leads to a deterioration of energy performance transducer with motor load.

AC to DC converters are known, containing at least one single-phase semi-controlled unsymmetrical thyristor rectifier, in the alternating current diagonal of which is connected the secondary winding of the transformer, and the switching circuit of the series-connected capacitor, drossel and thyristor connected in parallel to one of the thyristors bridge 2.

The known device has limited functionality, since It can not operate in the mode of intermittent currents.

The purpose of the invention is to expand the functional capabilities of the converter.

The goal is achieved by the fact that it is equipped with an additional switching circuit connected in parallel to another bridge thyristor, with the switching circuit capacitors connected to the common point of the bridge thyristors, and the common points of the capacitor and throttle of each switching circuit are connected via diodes to the corresponding pins of the bridge.

A schematic diagram of the device is shown in FIG. one.

The converter contains a transformer, the primary winding 1 of which is connected to the supply network, the secondary winding

2 - to the bridge diagonal, made on diodes 3 and 4 and thyristors 5, 6.

Thyristors 5 and 6 provide output voltage control by switching on with a given phase angle a.

Each thyristor is turned off by an individual switching circuit, formed by series-connected capacitor 7, 8, choke 9, 10, and thyristor And 12. 12. The connection point of the capacitor 7, 8 and throttle

9, 10 through diodes 13 and 14 is connected to the corresponding DC output of the bridge.

The Converter operates as follows.

The charge of the switching capacitor 7, 8 is made into a non-conducting for a given thyristor arm voltage half-cycle along the circuit: transformer winding 2, capacitor 7 (8), diode 13, (14) and diode 3 (4). To turn off the desired conductive thyristor 5 (6), turn on the corresponding switching thyristor, which creates a circuit for discharging the capacitor 7 (8) along the circuit; choke 9 (10), thyristor 11 (12), thyristor 5 (6). After the thyristor is locked, a load current flows through the capacitor 7 (8), recharging the capacitor to a voltage equal to the current voltage of the secondary winding 2 of the transformer, but opposite to polarity.

At this moment, a buffer circuit is created for the load current through the diode 3 (4) of the converter, and the magnetic field of the transformer energizes the capacitor 7 (8). If the voltage on the capacitor 7 (8) exceeds the amplitude value of the voltage of the winding 2 of the transformer, this excess energy will charge both capacitors 7 and 8, reducing the maximum operating voltage of the converter elements. Due to the overvoltage of the capacitor 7 (8) over the current voltage of the secondary winding 2, the capacitor 7 (8) returns the stored energy to the supply network through the secondary winding of the transformer, which further improves

energy performance converter.

FIG. Figure 2 shows a variant of the converter circuit when the transformer contains several secondary windings connected to series-connected rectifier bridges.

The operation of this scheme is similar to the one considered.

Claims (2)

1. Semiconductor rectifiers. Ed. F.I. Kovalev. M., "Energia, 1967, with. 64. 2. The patent of Austria No. 329687, cl. Н 02Р 7/29, published 1976. iput. 2